Full color-flat panel displays are essential for the development of many new devices such as notebook displays, signs, hand-held video displays and flat panel television. It has not yet been possible to make a multiple color liquid crystal display without the use of passive color filters or creating separate sealed compartments, each compartment containing a liquid crystal material that transmits or reflects a different color. This is typically done by stacking separate display cells, each containing cholesteric liquid crystal having a pitch length effective to reflect a different primary color. The necessity of preparing three separate display cells and providing them with suitable drive electronics complicates the manufacture and increases the cost of commercial devices. Moreover, the stacking of cells gives rise to an angular parallax between the individual colored cells which limits the useful viewing angle.
It has also not been possible to make a black and white reflective material suitable for devices requiring high quality black and white reflective displays. A white on black or black on white reflective display currently does not exist on the market to the knowledge of the inventors. Many new devices such as cellular telephones, electronic books and the like require reflective black and white displays for commercial viability.
The invention overcomes the drawbacks of known color displays and, for the first time, provides a good black and white reflective material. In particular, the invention provides a method of pixelizing a chiral nematic liquid crystal material whereby each pixel can be made to reflect a different color. By pixelizing the liquid crystal material itself, a single display cell can be divided into a matrix of different colors that can be separately modulated to create a high-resolution image in full color, or modulated in combinations that appear white. This innovation provides a low-cost means of making high-resolution multicolor displays and active (i.e. switchable) color filters, which obviates the problems associated with known technologies and for the first time enables the production of a black and white reflective flat-panel display.